JPH01277245A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve an electrostatic charge characteristic by incorporating >=40atomic% hydrogen into an a-Si film and specifying the alpha(SiH2)/alpha(SiH) value to 1.3-2.5. CONSTITUTION:A photoconductive layer 4 is constituted of the amorphous silicon which contains >=40atomic% hydrogen and has 1.32.5 ratio alpha(SiH2)/alpha(SiH) of the absorption coefft. alpha(SiH2) of the absorption appearing at about 2,100cm<-1> derived from the SiH2 bond of IR absorption spectra and the absorption coefft. alpha(SiH) of the absorption appearing at about 2,000cm<-1> derived from the SiH bond. Such a-Si film has the dark specific resistance as extremely high as 10<12>OMEGAcm even if boron, phosphorus or the like is not doped to the film. The photosensitive body having the sufficient photosensitivity and the excellent electrostatic charge holding power is, therefore, obtd. by using such film as the photoconductive layer 4 of the electrophotographic sensitive body.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electrophotographic photoreceptor used in an image forming apparatus using electrophotography.

<Prior Art> Recently, a photoconductive layer formed on a conductive substrate is made of amorphous silicon (a-
8i') has been proposed. This a
The -8i photoreceptor has a long life, which has made its practical use desirable due to the following advantages.

■ It is harmless to the human body.

■ High sensitivity.

As such a-3i photoreceptor,
As stated in Publication No. 59, a of the photoconductive layer
- To form the 8i layer, plasma CVD method and spackle method are used, and the amount of hydrogen is 10 to 40a.
It is specified that it is optimal to set the value to tomic%.

<Problems to be solved by the invention> In the conventional a-8i photoreceptor, hydrogen (H) in the a-3i layer
The amount is strictly defined to be 10 to 40 atomic% as described above. Also, lO ~ 40 atoms
In the a-8t film containing c% of hydrogen, the absorption coefficient α (SiH2) derived from SiH2 bonds in the infrared absorption spectrum near 2100α and 5i
The ratio α (S i −H2
)/α(Si H2) is approximately 0.2 to 1.7, as disclosed in Japanese Patent Application Laid-Open No. 158650/1983. If an attempt is made to maintain sufficient photosensitivity for such an a-8i electrophotographic photoreceptor, its specific resistance will be 100, and even if it is doped with boron (CB), it will be as small as 10 Ωα. Therefore, compared to existing selenium and OPC photoreceptors, the charge retention ability was inferior.

Alternatively, when trying to improve the charge retention ability, the absorption coefficient ratio α (SiH2
)/α(SfH) needs to be increased. However, in the plasma CvD method and sputtering method, increasing the high-frequency power during film formation activates the reaction in the gas phase of the raw material gas, resulting in the generation of a large amount of 5iH2)n polymer powder. The film adheres to the substrate of the photoreceptor, preventing normal film growth and rendering the photoreceptor a defective product. Furthermore, in the conventional manufacturing method, the film forming speed is very low and it takes a long time to prepare the photoreceptor, making it impossible to reduce costs.

Means for Solving the Problems〉 The electrophotographic photoreceptor of the present invention has water X(H) on a conductive substrate.
In an electrophotographic photoreceptor formed with a photoconductive layer made of amorphous silicon containing 40 atomic% or more of hydrogen, the absorption coefficient of absorption appearing around 2100 Lv derived from SiH2 bonds in the infrared absorption spectrum (
α5iH2) and 2000- derived from SiH bond.
The ratio of the absorption coefficient (α5iH) of the absorption appearing nearby (
The photoconductive layer is made of amorphous silicon (a-8i) with αSiH+/α5iH) of 1.3 to 2.5.

Further, the above a Si layer is formed by an electron cyclotron resonance method.

Effect> According to the electrophotographic photoreceptor of the present invention, 210 (1
The absorption coefficient a' (SiH2
) and the absorption coefficient α(S iH) of absorption appearing around 2000- derived from SiH bond
An a-8t film with iHz )/α(SiH) of 1.3 to 2.5 has a very high dark specific resistance of 10 12 Ω even though it is not doped with boron or phosphorus. By using this as a photoconductive layer of an electrophotographic photoreceptor, a photoreceptor having sufficient photosensitivity and excellent charge retention ability can be created.

Furthermore, by producing this film using the electron cyclotron resonance method, the yield rate and film forming rate can be increased, and costs can be reduced.

<Example> FIG. 1 is a cross-sectional view showing the layer structure of an electrophotographic photoreceptor according to the present invention, and FIG. It is a sectional view showing a membrane device.

First, in FIG. 2, the film forming apparatus has a plasma chamber +1 for generating hydrogen plasma, for example, and a deposition chamber 12 for depositing an a-3+ layer.

The plasma chamber 11 and the deposition chamber 12 communicate with each other through a plasma extraction window 13, and are evacuated by an oil diffusion pump and an oil rotary pump (not shown).

The plasma chamber 11 has a cavity resonator configuration, and a 2.45 GHz microwave is introduced from a waveguide 14. Note that the microwave introduction window I5 is made of a quartz glass plate through which microwaves can pass. H2 gas is introduced into the plasma chamber 11 through an introduction pipe 17. A magnetic coil 16 is arranged around the plasma chamber 11 . magnetic coil 1
6 generates plasma and forms a diverging magnetic field for drawing out the plasma generated in the plasma chamber 1 to the deposition chamber 12.

A conductive substrate 18 made of aluminum (An) is installed in the deposition chamber 12. In this embodiment, the conductive substrate 18 is made of aluminum (An).
Since it is drum-shaped, it is supported by a support and rotated.

A source gas is introduced into the deposition chamber 12 through an introduction pipe 19 . As this raw material gas, for example, SiH4+ 5i
zHa, 5iFa.

It is a silicon compound containing hydrogen I, such as 5iC14, 5iHC13, 5iHzC1z, or a gas mixture thereof. In the figure, 20 is a microwave oscillator, and 21 is a lamp for heating the conductive substrate 18.

With this configuration, first, the plasma chamber 1 is
1 and the deposition chamber 12 are evacuated, the plasma chamber 11C is supplied with H2 gas via the introduction pipe 17, and the deposition chamber 12 is supplied with H2 gas via the introduction pipe 17.
The above-mentioned raw material gases are respectively introduced through 9. The gas pressure at this time is set to 10-3 torr to 10 torr. Here, microwaves from the oscillator 20 are introduced into the plasma chamber 11, and a magnetic field is also applied to excite the plasma. The plasma H2 and source gas are guided to the conductive substrate 18 by the divergent magnetic field, and a-8i is deposited on the surface thereof. Since the support is rotated, a film is uniformly formed on the conductive substrate 18. Furthermore, by adjusting the position and size of the plasma drawer window, a
It is possible to improve the uniformity of the −8t film.

In such a film forming apparatus, a film forming experiment was conducted using 5 in 4 gas as a raw material gas and varying the gas pressure. This a-8
Absorption coefficient ratio α(SiH2)/α(SiH)・bright conductivity (ημτ
)・Dark specific resistivity CP, () dependence on gas pressure is shown in graphs in FIGS. 3, 4, and %5, respectively.

As shown in these, the absorption coefficient ratio α(SiH2)/
By setting the value of α(SiH) to 1.3 to 2.5,
An a-3t film with a dark specific resistance of 100 or more and high bright conductivity (high photosensitivity) was created. In this way, the a-8t film, which has a dark specific resistance of 10 Ω1 or more and high bright conductivity (high photosensitivity), has a conventional H content of 40 atomic% or less, α(SiH2)/α(S
An a-8i film with an iH) value of 0.2 to 1.7 could not be achieved.

As a result of further repeated experiments, α(S'iH
When the value of 2)/α(SiH) is set to 1.3 to 2.5 and the amount of hydrogen in the film is set to 40 atomic % or more, the effects of the present invention are further enhanced. However, the amount of H in the a-8i film is reduced to 60 atoms.
It has been found that when the concentration exceeds c%, the optical band gap of the film becomes too large, making it unsuitable as a photoconductive layer for an electrophotographic photoreceptor that requires photosensitivity to visible light. , the amount of H in the film is preferably 40-60
atomic%, most preferably 40-50 atomic%
The value is mic%.

As shown in Figure 2, according to the film formation according to the present invention, it is created by the electron cyclotron resonance method, and no (SiH2)n powder is generated at all, and the film formation speed and gas usage efficiency are Both are 6 to 10 times lower than the conventional method.
In addition, the a-8i film according to the present invention can be used from external sources such as the photoconductive layer of an electrophotographic photoreceptor, the photosensitive part of an image sensor, and the photosensitive part of a display element laminated with a liquid crystal. It is most suitable for the photosensitive part of a device that converts optical information into electrical signals. Furthermore, it can also be applied to devices such as solar cells and thin film transistors.

Next, the amount of H in the film according to the present invention was reduced to 40 atomic
An example will be described in which an a-8t film containing at least % of the a-8t content is used as a light guide layer of an electrophotographic photoreceptor.

(Example 1) In order to obtain a positively charging electrophotographic photoreceptor 1 having the structure shown in FIG. 1, an intermediate layer 3, a photoconductive layer 4, and a surface coating layer 5 are formed in this order on a conductive substrate 2. did.

That is, the photoconductive layer 4 should contain hydrogen, have an absorption coefficient ratio α(SiH2)/α(SiH) of 2.15 at 2100 cm 2 and 2000 ctn in the infrared absorption spectrum, and be doped with a small amount of poron (B). , electron, cyclotron Φ resonance method a-8i
Furthermore, the surface coating layer 5 is an a-8iC film made by the electron cyclotron resonance method, and the intermediate layer 3 is an a-3i film made by the same method and heavily doped with boro/. A positive charging photoreceptor was fabricated using the following method.The fabrication conditions at this time are summarized in Item 1 below.

Table 1 As a gas for doping boron, B2H6°B
A compound of boron and hydrogen such as H3 is preferred. Also, suitable atoms having the same function as boron include aluminum, gallium, and indium. At this time(
No SiH2)n powder was generated, and both the film forming speed and gas utilization efficiency were 6 to 10 times higher than conventional methods. Furthermore, when the characteristics of the produced photoreceptor were measured, it was found that the charging characteristics were particularly excellent compared to the conventional a-8i photoreceptor. Further, when this was installed in a commercially available positively charging copying machine and an image was produced, a good image was obtained. Further, when the amount of H contained in the a-8i film described in this example was measured, it was found to be 48 atomic%.

Note that good results have also been obtained when an a-8iN film or an a-3iO film prepared by the electron cyclotron resonance method is used as the surface coating layer 5.

(Example 2) Only the gas pressure during photoconductive layer formation was changed, and all other conditions were the same as in Example 1.Table 2 As described in Cloth 2 above, the gas pressure was selected and α( S 1H2)
/α(SiH) value from 1.3 to 2.5 (see Figure 3)
At the beginning, good results were obtained.

In addition, the amount contained in the photoconductive layer of each sample (photoreceptor) is excluded.

As a result of measuring the H content, the gas pressure was 2.8 to 3.4 m.
at torr, 45-52 atomic%,
3.8-5, 20-30 atoms at 0 mtorr
The value was ic%.

(Example 3) The photoconductive layer 4 contains 46 atomic% of H,
Furthermore, the a-8i film made by the electron cyclotron resonance method doped with a small amount of phosphorus (P), and furthermore, the surface coating film 5 is
A-8 created by cyclotron resonance method
A photoreceptor for negative charging was prepared which included an iC film and an a-8t film prepared by the same method and doped with a large amount of phosphorus (P) as the intermediate layer 3. The preparation conditions at this time are summarized in Table 3.

Table 3 PH3゜PC13 as a gas for doping phosphorus
, PCt5, or their compounds are suitable. Also, suitable atoms that have the same function as phosphorus include nitrogen, antimony, and oxygen.

At this time, (SiH2)n powder was not generated at all, and both film forming speed and gas utilization efficiency were significantly higher than those of the conventional method. Furthermore, when the characteristics of the produced photoreceptor were measured, it was found that it was particularly excellent in charging characteristics. Also, when this was installed in a commercially available negatively charged copying machine and image output was performed, a good image was obtained.

In addition, as a surface coating layer, electron, cyclotron,
a-3iN film or a made by resonance method
Good results were also obtained using the -8iO film.

Effect> According to the electrophotographic photoreceptor of the present invention, 40
Contains atomic% or more hydrogen and a (S 1H
2) The /α(SiH) value is set to 1.3 to 2.5, so it has sufficient photosensitivity and has a very large dark resistivity, making it a photoreceptor with particularly excellent charging characteristics. can be created.

In addition, by creating the a-8i film according to the present invention by the electron cyclotron resonance method, (
No SiH2)n powder is generated, and the film forming speed is low.
Both gas utilization efficiency values were significantly higher than those of the conventional method, and a
-8t Nausea can be produced at low cost.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the structure of an electrophotographic photoreceptor according to the present invention, FIG. Figure, Figure 4. and Figure 5 shows α(SiH2)/α in the film versus gas pressure.
(SiH) value, groove electrical conductivity (ημτ) and dark specific resistivity (9
It is a characteristic diagram showing d). 1: a-8i photoreceptor conductive substrate 2: conductive substrate 3: intermediate layer 4: photoconductive layer 5: surface coating layer agent patent attorney
Takeshi Sugiyama (and 1 other person) I-M number □2”a Of 234 5 J's pressure <mTorr) Figure 3 0 / 234 56 OZE (mT
Qrf)Ocean pressure (mrorr)

Claims (1)

[Claims] 1. In an electrophotographic photoreceptor comprising a conductive substrate and a photoconductive layer formed on the substrate and made of amorphous silicon (a-Si) containing hydrogen (H). , the photoconductive layer contains 40 atomic% or more of hydrogen, and the infrared absorption spectrum is 21 derived from SiH_2 bonds.
The absorption coefficient α (S
iH_2) and 2000cm^-^ derived from SiH bond
Ratio α of absorption appearing near 1 to absorption coefficient α (SiH)
(An electrophotographic photoreceptor comprising an amorphous silicon having SiH_2/α(SiH) of 1.3 to 2.5.